NEW YORK, May 18 (Thomson Reuters Foundation) - Jennifer Kempton, a former sex slavery victim who founded the U.S.-based charity Survivor's Ink to help other trafficked women, died on Thursday, an associate said, prompting a series on tributes on social media.

Kempton used tattoos to cover up those branded on her by sex traffickers and she founded her non-profit group in 2014 to provide grants so others could do the same.

Kempton, who lived in Columbus, Ohio, died on Thursday morning, according to Paula Haines, executive director of Freedom a la Cart, a catering and box lunch company that trains and employs trafficking survivors.

Kempton previously worked at Freedom a la Cart, and both organizations often worked with the same survivors, Haines said.

Local police said they received a report of an accidental drug overdose and took Kempton, unconscious and unresponsive, to an area hospital late on Wednesday night.

Police did not have official confirmation that Kempton died, and the hospital, Mount Carmel West, did not respond to a request for information.

Kempton, who often spoke publicly about her experiences, aimed to help survivors whose traffickers had tattooed or branded them to show ownership and control.

Globally some 4.5 million people are trapped in sexual exploitation, according to the United Nation's International Labour Organization, generating an estimated $99 billion in illegal profits a year.

"It's always amazing to see the look on their face when they no longer have to look at this dehumanizing mark of ownership and violence," Kempton told the Thomson Reuters Foundation in an interview last year.

"Sometimes I'll get a call a few days later with someone just bawling their eyes out saying 'Oh my gosh, I can actually look at my body. It's my own again.'"

Kempton said on her neck had been tattooed with the name of one of her traffickers along with his gang insignia and above her groin were the words "Property of Salem," a former boyfriend who forced her into prostitution.

Her trafficker got her addicted to heroin and plied her with crack cocaine so she could work long hours. She was a prostitute on the streets of Columbus for six years.

She said she transformed the tattoo on her neck into a large flower, and other brandings were masked with decorative motifs.

Requests for tattoos came from around the world, and Kempton told the Thomson Reuters Foundation that last year she helped a woman in Britain whose mother had carved the word 'whore' into her leg when she was a child and sold her.

Speaking last month at Trust Conference/America Forum, an anti-slavery and trafficking event run by the Thomson Reuters Foundation in Washington, D.C., Kempton said survival remained a daily challenge.

"Once we escape, there is a whole new hell," Kempton said. "You can rescue us all you want, but what we need is opportunity. We want jobs, we want education, we want choices, we want our children back.

"There needs to be more start-up money for survivors who want to start up their own businesses."

No other details about Kempton's family were immediately available but tributes to her were made on Twitter. "RIP Jennifer Kempton, you suffered so much in this life and did so much for others," said a tweet from In Our Backyard, a U.S.-based non-profit that fights human trafficking.